@@ -210,6 +210,11 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
struct vhost_virtqueue *vq = ubufs->vq;
int cnt = atomic_read(&ubufs->kref.refcount);
+ /* set len to mark this desc buffers done DMA */
+ vq->heads[ubuf->desc].len = success ?
+ VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
+ vhost_ubuf_put(ubufs);
+
/*
* Trigger polling thread if guest stopped submitting new buffers:
* in this case, the refcount after decrement will eventually reach 1
@@ -220,10 +225,6 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
*/
if (cnt <= 2 || !(cnt % 16))
vhost_poll_queue(&vq->poll);
- /* set len to mark this desc buffers done DMA */
- vq->heads[ubuf->desc].len = success ?
- VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
- vhost_ubuf_put(ubufs);
}
/* Expects to be always run from workqueue - which acts as
This is a note to let you know that I have just added a patch titled vhost_net: poll vhost queue after marking DMA is done to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.11. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From dc0f635dd95bcd4a2087e9e44f2fa54cf5fbd9c4 Mon Sep 17 00:00:00 2001 From: Jason Wang <jasowang@redhat.com> Date: Mon, 2 Sep 2013 16:41:00 +0800 Subject: vhost_net: poll vhost queue after marking DMA is done [ Upstream commit 19c73b3e08d16ee923f3962df4abf6205127896a ] We used to poll vhost queue before making DMA is done, this is racy if vhost thread were waked up before marking DMA is done which can result the signal to be missed. Fix this by always polling the vhost thread before DMA is done. Signed-off-by: Jason Wang <jasowang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> [ kamal: backport to 3.8 ] Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/vhost/net.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) -- 1.8.1.2